This invention relates to antiperspirant compositions of the so-called dry-feeling type, comprising an emulsion of an aqueous solution of an astringent in a volatile, water-insoluble liquid and having improved efficacy.
Antiperspirant compositions are well known in the cosmetic art. These compositions are formulated as aerosols, gels, sticks, creams, pump sprays and lotions and comprise an astringent, typically comprising one or more zirconium salts and/or aluminum salts, in various forms such as a dry, impalpable powder, an alcohol solution or an aqueous solution. Of these various forms of astringents the aqueous solution is generally considered to be the most effective antiperspirant.
However, an antiperspirant composition having water as the continuous phase, such as an aqueous solution of an astringent, or an oil-in-water type emulsion thereof, is less desirable than a composition comprising a dry powder or an alcohol solution thereof because it tends to feel wet when applied to the human skin and to go through a tacky state during the drying period after application.
U.S. Pat. No. 4,122,029 discloses water-in-oil type compositions having broad utility and comprising a polydiorganosiloxane-polyoxyalkylene copolymer and a water-in-oil type surfactant. When formulated as an antiperspirant emulsion of an aqueous solution of an astringent such as aluminum chlorhydrate emulsified in a volatile, non-aqueous continuous phase, these compositions have a desirable dry feeling when applied to the human skin and do not exhibit the wet-and-tacky effect noted above.
U.S. Pat. No. 4,268,499 discloses compositions described as having greater efficacy than those of U.S. Pat. No. 4,122,029. The efficacy was determined by applying compositions to subjects' wrists and measuring the time required for the compositions to begin to dry and turn white. This "whitening" is a characteristic of antiperspirants of the "dry-feeling" type which the consuming public has found objectionable because of the visibility of the white area on uncovered skin, and the tendency of the active ingredient to fall off the skin, which reduces the efficiency of the product and may also cause unsightly stains if the active ingredient falls on the fabric of clothing.